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Understanding Macronutrients & How They Work Together

By Nikita Soldi, Personal Trainer at Wollongong

We all know each of our macronutrients are important for their own individual reasons, but what about how each of these macronutrients work off each other to function too? Each of our macronutrients work together to provide the body with energy throughout a day-to-day basis. Although the body prioritises carbohydrates as its main source of energy, energy from fat will also be used, especially when in a calorie deficit.

As a refresher, I will talk you through the individual reasons for why we need to have a well-rounded diet that includes all three macronutrients.

The Role of Carbohydrates

The main function of carbohydrates is to provide energy to the body. When consumed, carbohydrates are broken down into simple sugars known as glucose. The glucose will then either be used for immediate energy for general movement, or activity, or stored in the muscles and liver for later use. Glucose is also essential for optimal function of the brain and nervous system. Without it, you may experience confusion, and/or brain fog. When multiple single glucose molecules are being stored in the muscles and livers, they branch onto one another, creating glycogen. When the body needs a quick boost of energy, the stored glycogen gets broken back down into single glucose molecules and released into the blood stream for energy use. It will mainly be used for intense activity. Starchy foods (bread, rice, pasta, to name a few) are vital for optimal nutrient value. The main micronutrients provided from starch are calcium, iron, B group vitamins and folate. Fibre is essential for optimal function of the digestive system. Its job is to travel through and clean the body of bacteria. A diet high in fibre is essential for regular bowel movement. Without a sufficient amount of dietary fibre, one may experience constipation. Carbohydrates are also the most water dense macronutrient. Lack of carbs may result in dehydration.

The Role of Protein

The main functions of protein are muscle growth and maintenance, production of some hormones, immunity, transportation, and to provide satiety. Protein is used as building blocks to help form and maintain our muscles, tendons, blood, skin, hair, bones, and some organs. To repair and maintain these structures, one must continue to consume protein through the diet. Lack of protein may cause changes in appearance to hair, skin and nails. Loss of muscle mass may also cause a decrease of metabolic rate, and therefore may make fat loss harder. This may also lead to muscular weakness. Protein also has the responsibility of regulating and keeping human insulin levels at a balanced level. Insulin is used to control glucose levels (which are used for energy production or energy storage). Protein forms the structure of immune system antibodies. Without these antibodies, the body won’t be able to fight of foreign invaders or diseases. Without sufficient protein intake, the body may become more susceptible to colds and flu. Protein helps to transport certain fats, vitamins, minerals, and oxygen throughout the body. They are carried out around the body by protein structures. Without an optimal consumption of protein, these things won’t be carried out to make use of their normal functions. Protein is the only macronutrient that causes satiety. It can effectively send a message to the brain to let it know it is full, and to stop eating. Satiety helps curve cravings of fatty and high carb foods, which becomes ideal for those with fat loss goals.

The Role of Dietary Fat

Dietary fats are essential for many body processes. Essential fatty acids in particular are needed to produce important hormone regulators, production of dietary cholesterol, transportation of vitamins A, D, E and K, optimal insulation and balancing blood sugar levels. Eating a low fat diet decreases the production of our estrogen, progesterone and serotonin. Estrogen and progesterone rely on the production of dietary cholesterol. Lack of estrogen production may lead to insomnia, night sweats and/or heart palpitations. Low levels of progesterone may cause irregular or absent menstrual cycles, mood changes and/or headaches. although that may not be a problem for males, low fat diets may inhibit the body from making serotonin. Lack of serotonin may cause low mood and low quality sleep. Our vitamins A, D, E and K are called our fat-soluble vitamins. This means it can only be absorbed with the appearance of fats. With the absence of fats, these vitamins are essentially useless as they cannot be absorbed to perform their functions. Insufficient quantities of these vitamins may have a negative effect on vision, bone health, immune function as well as many other functions. Fat is also responsible for regulating a normal body temperature. Fat stored on the body helps provide insulation and warmth to vital internal organs. Fat is responsible with stabilising blood sugar levels. An absence of fat may cause sugar cravings, and when indulged, may lead to an energy crash.

How Each Macro Works Together

Although each macronutrient is important for their own purposes, to optimise maximal health, a well-rounded diet with all three macronutrients is needed. As shown above, each macronutrient is essential for their own individual functions, but they also work better with the assistance of each other. When it comes to energy, each macronutrient plays a vital role in working together to ensure optimal use of our energy needs. As we know, carbohydrates provide us with our main source of energy. When this energy is needed, our body uses the stored energy (glycogen), but first needs to be broken down. To do this, protein enzymes are used to break them down into single sugars (glucose) which are then sent into the blood stream to be used as immediate energy. As mentioned earlier, the protein hormone, insulin, is used to control glucose levels. Insulin sends an effective message to glucose to tell it to either be used as immediate energy, or to be stored as glycogen in our muscles for later use. Although protein can provide energy to the body it is not ideal to use this as an energy source. If the body uses protein for energy, it can chew into our muscle mass, resulting in a slower metabolism. Keeping a sufficient intake of carbs will ensure we use that as energy rather than protein. Carbohydrates help the protein to maintain and even build lean muscle mass. Due to protein and fat having slower absorption rates, it helps our carbohydrates to store at a slower rate. With this, our energy levels become more consistent through the day. This will result in less energy fluctuations, and in turn will accelerate fat loss. A well-rounded diet will ensure that our body receives a wide range of our vitamins and minerals. Our vitamins A, D, E and K are consumed through a variety of protein and carbohydrate sources. But, to ensure that these vitamins are absorbed, so they can do their bodily functions, they must be consumed with dietary fats. With the absence of these dietary fats, these vitamins simply cannot be absorbed to do their job. This may lead to certain deficiencies. From this I hope you can see that regardless of your goals, having a balance of all three of these macronutrients will give you the best chance of maintaining a healthy body.

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